Unitized well head



Jan. 24, 1967 w.1 TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 1 mvsm'on WILLIAM L 1000 ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 2 F'IE'| 2 24 INVENTOR WILLIAM L. TODD 2O BYW/M ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 5 F'IIIiJI-l INVENTOR 2O WILLIAM L. r000 ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 51, 1962 9 Sheets-Sheet 4 FIB Q mvzu'ron 2O WILLIAM L. T000 ATTORNEY BY New 2%. /W

Jan. 24, 1967 W. L. TODD 3,299,958

UNITIZED WELL HEAD I Original Filed Jan. 31, 1962 9 Sheets-Sheet 5 2O 0 WILLIAM L. TODD,

ATTORNEY Jan. 24, 1967 w. TODD I 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 6 INVENTOR WILLIAM L. TODD ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD orlginal Filed Jan. 51, 1962 9 Sheets-Sheet 7 I INVENTOR WILLIAM TODD ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 8 INVENTOR WILLIAM L. TODD ATTORNEY Jan. 24, 1967 w. L. TODD 3,299,958

UNITIZED WELL HEAD Original Filed Jan. 31, 1962 9 Sheets-Sheet 9 FIE EI 4 INVENTOR 54 WILLIAM L. TODD ATTORNEY United States Patent Oflice 3,299,958 Patented Jan. 24, 1967 3,299,958 UNITIZED WELL HEAD William L. Todd, Pasadena, Calif., assignor to FMC Corporation, San Jose, Calif., a corporation of California Continuation of abandoned application Ser. No. 170,090, Jan. 31, 1962. This application Apr. 2, 1965, Ser. No.

18 Claims. (Cl. 166-89) This application is a continuation of my prior copending application Serial No. 170,090, filed January 31, 1962, for Unitized Well Head, now abandoned.

This invention pertains to well heads and more particularly relates to apparatus installed at the upper end of a well which is supported by the surface casing of the well and which carries the oil casing and the production tubing of the well.

In the drilling and construction of a well, particularly an oil or gas well, in accordance with conventional practice, the well bore is started and the surface casing set or cemented in place whereupon a casing head is installed thereon. A blowout preventer is secured to the casing head, and the drilling operation is then resumed, drilling mud being circulated in the usual manner. The well bore may pass through one or more producing zones, either gas or oil. When the desired depth is reached, the drill pipe is removed and one or more oil casing strings and the tubing string or strings are lowered into operating position. The oil casing strings are supported by a casing hanger installed within the casing head. It is understood that various other operations are carried out, such as perforating and/or installing a liner. Then the blowout preventer must be removed and finally, a tubing head and the production tubing installed. During the period after the blowout preventer has been removed and before completion of the installation of the tubing head and production tubing strings, the well, which is then open, is in a very critical and dangerous condition. This is particularly true in the case of deep and high pressure wells which are prone to develop pressures resulting in a blowout. In oil well practice, a well is not considered open as long as a blowout preventer is in place even though the blowout preventer may be retracted, since the blowout preventer is available to seal the well if needed.

An object of the invention is to provide a well head arrangement which is more compact, stronger and less prone to leak than prior conventional equipment.

Another object of the present invention is to provide a unitized casing and tubing head structure which permits the drilling and completion of the well without requiring that the well be open to atmosphere at any time.

Another object of the invention is to provide a unitized well head structure wherein the blowout preventers are carried in operating position throughout the drilling and completion operations of the construction of the Well and wherein the blowout preventers are not removed until after the production strings have been installed in the well and sealed to the casing head.

Another object of the invention is to provide a well head construction as set forth above permitting unobstructed access to the casings during the drilling operation and to the tubing strings at any time during the life of the well.

Another object of the invention is to provide a well head construction of the character referred to which is adapted to be used in connection with artificial production methods such as gas lift methods of inducing flow from a well wherein parallel strings of tubing are employed, one string being used to introduce gas under pressure in order to lift fluid through the other string or strings.

These and other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a diametric section through a well head comprising the principles of the present invention.

FIGURES 2-9 are a diagrammatic representation of the well head construction of the present invention, illustrating the order in which the several elements are installed therein.

The several components which make up the well head assembly will be described in conjunction with a description of the procedure of drilling and completing a well.

A surface or support casing 20 is installed and cemented in place in the usual manner. A combined unitized casing and tubing head 22 (FIGS. 19) is then fastened to the upper end of the surface casing 20 by threads 24 (FIG. 1) or any other suitable means of connection such as welding.

A lower blowout preventer 26 (see FIG. 2) is fastened to the upper end of the unitized head 22 by way of eX- ample by a union type fastening nut 28 which is screwed onto threads 30 on the upper end of the head 22, and is equipped with a inturned lip 32 which embraces a flange 34 on the lower end of the blowout preventer 26. Any suitable flange or clamp type connection could be used. A sealing gasket 36 is provided between the upper end of the unitized head 22 and the lower end of the blowout preventer 26.

A mud cross assembly 38 is fastened to the upper end of the blowout preventer 26 by a conventional flange connection 40. A second blowout preventer 42 is fastened to the upper end of the mud cross assembly 38 by a conventional flange connection 44. A funnel-shaped mud return assembly 46 is fastened to the upper end of the blowout preventer 42 by a conventional flange connection 48. The mud return assembly 46 has a lateral opening through which drilling mud flows to a mud return conduit 50.

Drilling is then resumed in the usual manner with the mud being pumped down through the drill pipe which extends through the bore 52 through the several elements already described and returns through the annulus surrounding the drill string and is carried by the conduit 50 back to the mud pit.

After the drilling has been completed because the well has reached the desired depth, the oil casing string 54 (FIG. 3) is installed in the well and is supported therein by a casing hanger assembly 56 which may be of the type employing a slip bowl 58 resting on a ledge 60 formed in the unitized casing head 22 and slips 62 engaging the outer surface of the oil casing 54 to support it within the well. On the other hand the casing hanger may be of the mandrel type (not shown).

After the casing hanger 56 has been installed a conventional casing cutter 70 (FIG. 3) is lowered within the casing 54 by a mandrel 72 and the casing 54 is cut off at a desired elevation above the casing hanger 56.

An opening 80 in the unitized head 22 provides communication with the annulus between the oil casing 54 and the surface casing 20. The annulus is sealed by means of a packotf bushing 82 (FIG. 4) which is installed within the unitized head 22 by a mandrel (not shown) which engages J-slots 83 in the bushing 82. The bushing 82 is provided with interior O-rings 84 which seal against the outer surface of the part of the oil casing 54 which projects above the casing hanger 56. Two sets of external O-rings 86 and 88 seal against the interior wall of the head 22 above and below a lateral opening 90 therein. The opening 90 provides communication with the interior of the oil casing 54 through a port 92 in the packoif bushing 82. A vertical slot 94 in the outer surface of the lower portion of the packoff bushing 82 cooperates with a retractable aligning pin 96 carried by the unitized head 22 to properly orient the packoff bushing with respect to the head so that the port 92 therein will be in register with the port 90 in the head. Similarly, a retractable lock down pin '98 is mounted in the unitized head 22 and is adapted to be projected inward into a groove 100 formed in the periphery of the packoff bushing 82 to lock the same within the head 22. While only one look down pin 98 is shown in the drawings, it should be realized that several of these lock down pins are used.

After the packoif bushing 82 has been installed and locked down within the head 22, the first tubing string 110 (FIG. is lowered into the casing 54. Before the final section of the tubing string is lowered into position, it is screwed into the lower end of a passageway 111 through a tubing hanger assembly 112, and the tubing and hanger assembly is lowered until the tubing hanger assembly 112 is seated within a conical support surface 118 for-med at the upper end of the packoif bushing assembly 82 (FIG. 6). A vertical slot 113 (FIG. 1) is formed in the lower portion of the hanger 112 and cooperates with an aligning pin 115 (FIG. 5) in the packolf bushing 82 to properly orient the hanger 112. It will be noted that the lower end of the tubing hanger assembly 112 is provided with a downwardly projecting cylindrical portion 120 having a sealing element 122 mounted thereon. This cylindrical portion 120 slides within the counterbored upper portion 124 of the packoff assembly 82, the sealing ring 122 being squeezed into sealing engagement with the wall thereof (FIG. 6). A plurality of lock down pins, one of which is shown at 126, carried by the unitized head 22 are screwed inward to seat within a peripheral groove 128 formed in the outer surface of the hanger assembly 112 to retain the same within the head 22.

A back pressure valve assembly 114 is latched within the tubing hanger 112 and a mandrel 116 is threaded into the upper end of the passageway 111 in the tubing hanger assembly 112.

The second string of tubing 130 (FIG. 7) is lowered through a second passageway 132 (FIG. 6) of the tubing hanger 112. The upper end of the string 130 is screwed into the lower end of a tubing hanger 134 which is received within the bore 132 and rests upon a shoulder 136 provided therein. Two O -rings 135 are mounted on the hanger 134 and seal against the wall of the bore 132 in the hanger 112. A back pressure valve 138 is latched within the tubing hanger 134.

After the second tubing string 130 has been installed, the well is completely sealed below the blowout preventers by the packoif bushing 82, the tubing hangers 112 and 134, and the two back pressure valves 114 and 138 installed in the two tubing strings, respectively. It is then safe to remove the blowout assembly group. Two sealing nipples 140 and 142 (FIG. 8) seated within sockets formed in the upper end of the tubing hangers 112 and 134, respectively, project upward therefrom. A Christmas tree assembly 144, which may be of the type shown and described in the pending application of Jacob M. Lebeaux et al., Serial No. 755,470, now U.S. Patent No. 3,050,126, is then installed. The Christmas tree assembly 144 fits over the upper projecting ends of the nipples and 142, each of which is provided with O-ring seals on its outer peripheral surface to seal both with the tubing hangers and with the Christmas tree assembly. A nut 28a clamps the Christmas tree assembly to the upper end of the unitized head 22. After the Christmas tree assembly 144 has been installed, the back pressure valves 114 and 138 are removed therethrough (FIGS. 1 and 9) and after the drilling mud is displaced, the well is ready for production.

From the foregoing description it may be seen that the invention provides a well head construction which is capable of assembly and operation without requiring at any time that the well be open to atmosphere and subject to blowouts.

While a particular embodiment of the invention has been described herein it should be appreciated that various changes may be made therein without departing from the spirit of the invention as defined in the appended claims.

The invention having thus been described what is claimed and desired to be protected by Letters Patent is:

1. A well head assembly comprising a tubular head having a seating surface in the bore therethrough and an internal wall extending around said bore, said internal wall projecting a substantial distance above said seating surface to an upper end portion of the head, well control means coupled to said upper end portion of the head, said means having a wall surrounding a bore in communication with the bore in said head, a casing hanger seated on, said seating surface, a casing supported by and projecting above said casing hanger, said casing thereby having an upper portion surrounded by said internal wall, a packoif bushing resting on said casing hanger between and confronting said upper casing portion and said internal wall, sealing means sealing between said upper portion of said casing and said bushing and between said internal wall of said head and said bushing, a tubing hanger seated on said pack-off bushing, and a tubing string supported by said tubing hanger and projecting into said bushing and casing.

2. A well head assembly comprising a tubular head having a bore therethrough, said head having a seating surface in the bore and an internal wall extending around said bore, said head having a port opening into said bore above said seating surface, a casing hanger seated on said seating surface, .a casing supported by and projecting above said casing hanger, said casing thereby having an upper portion in opposition to and circumscribed by said internal wall, a pack-off bushing resting on said casing hanger between and confronting said upper casing portion and said internal wall, sealing means carried by said pack 01f bushig and sealing between said bushing and said upper portion of the casing, said bushing having a lateral passageway, means for aligning said passageway with said port in said head, spaced sealing means carried by said bushing and sealing between said bushing and said internal wall of the head above and below said passageway and port, a tubing hanger seated on said bushing, and tubing supported within said casing by said tubing hanger.

3. The assembly of claim 2 wherein said aligning mean-s includes a slot in said bushing, said slot facing said internal wall, and an aligning pin mounted in said head and projecting into said slot.

4. The assembly of claim 2 wherein said seating surface is generally frusto-conical and downwardly convergent, and wherein said pack-off bushing has an upper downwardly convergent frusto-conical seating surface on which said tubing hanger is seated.

5. In a well apparatus including a first casing projecting into a well, and a well control unit, a unitary casing and tubing head having an internal wall circumscribing a bore through the head, said head having a lower end portion coupled to the first casing and an upper end portion coupled to the well control unit, a casing hanger positioned in said bore and supported by said head, a second casing hung in the well by said casing hanger and having an upper end portion projecting above the casing hanger, a packing bushing positioned in said bore and supported on said casing hanger, said bushing having an outer wall confronting said internal wall of the head and an inner wall surrounding said upper end portion of the casing, a lower inner seal sealing between said upper end portion of the casing and said inner wall of the bushing, an outer seal sealing between the outer wall of the bushing and the internal wall of the head, a tubing hanger seated on the bushing, and tubing hanging from said tubing hanger within said second casing.

6. The well apparatus of claim 5 wherein said tubing hanger has a lower end portion fitted into said inner wall of the bushing, and an upper inner seal sealing between the lower end portion of the tubing hanger and said inner wall of the bushing.

7. The apparatus of claim 6 wherein said head has a port opening into said bore, wherein said bushing has a lateral passageway in registration with the port, wherein said lower end portion of the tubing hanger and said upper end portion of the casing are in spaced relation to each other and terminate respectively above and below said passageway wherein said outer seal is below said port and passagewy and wherein there is a second outer seal sealing between said outer wall of the bushing and said internal wall of the head, said second outer seal being located above said port and passageway.

-8. The apparatus of claim 7 wherein the lower end portion of the tubing hanger and said casing are of generally the same diameter.

9. The apparatus of claim 5 including means movable between a locking position precluding movement of the bushing and the tubing hanger upward relative to the head and a retracted position permitting such movement.

10. The apparatus of claim 9 wherein said locking means includes a pin mounted in said head for movement radially of said bore between locking and retracted position.

11. The apparatus of claim 5 wherein the outer wall of said bushing has a groove therein, wherein said tubing hanger has an outer wall confronting said internal wall of the head and also provided with a groove, a lower pin mounted in said head for movement radially of said bore between a locking position in the groove in said bushing and a retracted position out of said groove, and an upper pin mounted in said head for movement radially of said bore between a locking position in the groove in said tubing hanger and a retracted position out of said latter groove.

12. The apparatus of claim 5 wherein said bushing has a lateral passageway opening therethrough, wherein said head has a port in registration with said passageway, wherein said outer seal is below said port and passageway, and wherein there is a second outer seal sealing between the outer wall of the bushing and the internal wall of the head above said port and passageway.

13. The apparatus of claim 5 wherein said bushing has an upper downwardly convergent frusto-conical seat and a counterbore projecting downward from said seat; wherein said tubing hanger has an outer Wall confronting the internal wall of said head, a frusto-conical shoulder rested on the upper seat of the bushing, and a lower end portion fitted into said counterbore in the bushing; and wherein there is an upper inner seal between said lower end portion of the tubing hanger and said bushing.

14. In a well apparatus including a first casing projecting into a well, and a well control unit, a unitary casing and tubing head having an internal wall circumscribing a bore, a lower seat projecting from the wall inwardly and downwardly with respect to the bore, said bore being of substantially uniform diameter above the seat, said head having a lower end portion coupled to said first casing and an upper end portion coupled to said well control unit, an annular casing hanger supported on said seat, a second casing hung in the first casing by said casing hanger, a bushing overlying said casing hanger and projecting upward therefrom, said casing hanger and said bushing having maximum and minimum diameters, the maximum and minimum diameters of said casing hanger being respectively substantially the same as the maximum and minimum diameters of the bushing, said casing hanger and said bushing being immediately adjacent to and directly facing said internal wall of the head, said bushing and casing hanger minimum diameters being substantially equal to the outside diameter of said second casing, said head having a port therein, said bushing having a lateral passage in generally the same radial plane as said port and establishing communication between'said port and the interior of said second casing, said bushing also having an upper downwardly convergent frustoconical seat, a tubing hanger having an outer wall substantially engaging said internal wall of the head and a frusto-conical shoulder rested on said upper seat of the bushing, said tubing hanger bushing and internal wall of the head defining a potential upper leakage path therebetween, upper sealing means precluding fluid flow from said second casing through said upper leakage path, lower sealing means precluding fluid flow from said first casing upward past said bushing, a lower pin mounted in the head for movement radially of said bore into and out of a locking position engaging said bushing and precluding upward movement thereof, and an upper pin mounted in said head for movement radially of said bore into and out of a locking position engaging said tubing hanger and precluding upward movement thereof.

15. A well head apparatus comprising a tubular head having a bore and an internal wall extending around the bore, an assembly including first hanger means supported in the bore of the head and a first pipe hanging from said first hanger means, said internal wall projecting above said assembly, to an upper end portion of the-head; well control means coupled to said upper end portion of the head, said Well control means having a bore communicating with the bore in said head, said assembly having an upper annular portion projecting upward from said first hanger means and surrounder by and circumferentially spaced from said internal wall; pack-off bushing means supported in the bore in said head between said upper portion and said internal wall; means sealing between said upper portion and said bushing means and between said internal wall of the head and said bushing means; second hanger means supported in the bore in said head; and a second pipe hanging from said second hanger means and projecting into said bushing means and first pipe.

16. The apparatus of claim 15 wherein said upper annular portion has an outer cylindrical surface with a predetermined maximum outside diameter, wherein said bushing means has an inner cylindrical surface having a predetermined diameter greater than said outside diameter, and wherein said cylindrical surfaces of said upper portion and bushing means are in confronting relation to each other whereby said bushing means can be installed in the head after installation of said assembly.

17. The apparatus of claim 15 wherein said upper annular portion constitutes an upward extension of said first pipe.

18. A well head assembly comprising a tubular head having an internal wall surrounding a bore through the head, first hanger means supported in the bore of the head, said head having a port opening into the bore above said first hanger means, conductor means hanging from and projecting above said'first hanger means, said first pipe means thereby having an upper portion circumscribed by said internal Wall, pack-01f bushing means supported in said bore above said first hanger means between and confronting said upper portion of said conductor means and said internal wall, sealing means sealing between said bushing means and said upper portion of said conductor means, said bushing means having a lateral passageway communicating with the port in said head, spaced sealing means sealing between said bushing means and said internal wall of the head above and below said passageway and port, second hanger means supported in said bore above said bushing means, and a pipe hanging from said second hanger means within said conductor means.

References Cited by the Examiner UNITED STATES PATENTS 2/1959 Johnson 16688 10/1937 Shaffer et a1 16688 5/ 1938 McDonough et al 16689 6/1959 Gould 16689 7/1962 Word 16689 4/1965 Haeber 16689 FOREIGN PATENTS 8/1960 Germany.

CHARLES E. OCONNELL, Primary Examiner.

15 J. A. LEPPINK, Assistant Examiner. 

15. A WELL HEAD APPARATUS COMPRISING A TUBULAR HEAD HAVING A BORE AND AN INTERNAL WALL EXTENDING AROUND THE BORE, AN ASSEMBLY INCLUDING FIRST HANGER MEANS SUPPORTED IN THE BORE OF THE HEAD AND A FIRST PIPE HANGING FROM SAID FIRST HANGER MEANS, SAID INTERNAL WALL PROJECTING ABOVE SAID ASSEMBLY, TO AN UPPER END PORTION OF THE HEAD; WELL CONTROL MEANS COUPLED TO SAID UPPER END PORTION OF THE HEAD, SAID WELL CONTROL MEANS HAVING A BORE COMMUNICATING WITH THE BORE IN SAID HEAD, SAID ASSEMBLY HAVING AN UPPER ANNULAR PORTION PROJECTING UPWARD FROM SAID FIRST HANGER MEANS AND SURROUNDER BY AND CIRCUMFERENTIALLY SPACED FROM SAID INTERNAL WALL; PACK-OFF BUSHING MEANS SUPPORTED IN THE BORE IN SAID HEAD BETWEEN SAID UPPER PORTION AND SAID INTERNAL WALL; MEANS SEALING BETWEEN SAID UPPER PORTION AND SAID BUSHING MEANS AND BETWEEN SAID INTERNAL WALL OF THE HEAD AND SAID BUSHING MEANS; AND A SECOND PIPE HANGING FROM SAID SECOND HANGER MEANS AND A SECOND PIPE HANGING FROM SAID SECOND HANGER MEANS AND PROJECTING INTO SAID BUSHING MEANS AND FIRST PIPE. 